Using the principles of operant conditioning, variables will be studied which influence the development, functioning and elimination of ethanol as a reinforcer via the oral route for rats and Rhesus monkeys. Ethanol serves as a reinforcer when it is self-administered at rates and volumes that exceed those of its vehicle control, which is usually water. When ethanol functions as a reinforcer, it increases the frequency of behaviors that result in its presentation. Methods used in analyzing other reinforcers may be applied to ethanol. Variables that affect both whether and to what extent ethanol is a reinforcer may be categorized as past history factors (e.g., prior drug experience), current circumstances (e.g., food deprivation), and response consequences (e.g., ethanol concentration). These variables will be studied parametrically, i.e., across a range of values, and interactions among variables will be explored systematically. The objectives of this research are (1) to investigate functional relations between certain independent variables (e.g., prior ethanol drinking experience) and several dependent variables (e.g., response rate reinforced by ethanol presentation, volume of ethanol consumed); (2) to study interactions among these independent variables (e.g., both ethanol concentration and reinforcement schedule parameter will be varied); and (3) to assess the relative importance of the variables studied. These objectives will have three consequences. One will be the establishment of a nonhuman model of ethanol dependence. A second consequence will be the development of a systematized body of knowledge which may be used in the analysis of the complicated phenomena of human ethanol dependence. A third consequence will be determination of results which can resolve conflicts among published studies that used only a single parametric value for each independent variable (e.g., one ethanol concentration).